Receiving circuit



May 31, 1932. H. D. CURRIER RECEIVING CIRCUIT (k I Al HUEUEP.

Filed April 20. 1925 Patented May 31,1932

UNITED STATES- PATENT. OFFICE HIRAM D. ,CURRIER, OF CHICAGO, ILLINOIS, ASSIGNOR 'IO KELLOGG SWITGHBOABD AND SUTIPLY COMPANY, OF CHICAGO, ILLINOIS, -A CORPORATION OF ILLINOIS RECEIVING CIRCUIT f I Applieationfiled Apri1-20, 1925. Serial No. 2 4,321.

My invention relates to wireless telegraphy and telephony and resides particularly in certain novel circuitarrangements and apparatus for systems of this character. I

My invention as shown'is adapted for the reception of radio signals, however, it 1s not liniitedto receptive use only. It is an object ofmy invention to providea novel and improved organization of the elements comprising such a system which arrangement provides sharpness of tuning, ease of tuning,

power, andclearness in respect to the signals received.

My invention as illustrated in the circu t 16 diagram of the accompanying drawlngyls shown in a receiving circuit arrangement hav-' ing radio frequency amplification, and is particularly illustrated in connection with so called tuned radio frequency amplification, in which inductances are tuned or controlled by variablecapacities to permit the amplifi cation of the desired signals and the e rclusion of the undesired "signals. Priorsystems of this character 7 are generally provided with one tuning device or condenser per stage of radio frequency amplification. are objectionable in that they necessitate one tuning device per, stage of amplification, and where it is desired touse several stages of ,30 amplification, it is necessary to adjust atuntype; Each of these transformers comprise a primary winding,,a'secondary winding and a tertiary winding. 'AT and, AT represent audio frequency iron core transformers. The

radio frequency tubes 2, 3 and 4, as well as the Y detector tube 5 and the audio frequency tubes 6 and 7 are each provided with the usual filament, grid and plate elements.- I provide .rheostats R, 'R and- R for controlling the Such systems heating current applied to the'filaments of p the radio frequency audion tubes 2, 3 and 41 respectively. A rheostat R is provided for controlling the supply of heating current to the filament of detector tube 5, and a rheostat R for controllingthe supply of heating cur rent to the filaments of tubesfi and 7. M

The tertiary windings 8 and 9 of thetransformers of the first two stages of radio frequency amplification, are connected'together and bridged by a variable condenser 10, likewise, the tertiary windings 11 and 12 of the transformers of the third stage and the detector stage are connected together and bridged by a variable tuning condenser :13. I provide the. usual grid leak 14 and grid condenser 15 in the grid circuit of the detector tube 5. The primary of the audion frequency transformer AT is bridged by a small condenser 17. At 18, I have shown a,

pair of receiversin the plate circuit of the second audio tube. This may be replaced by the usual loud speaker now in use. The battery 19 is the usual A battery for supplying heating current to the filaments of the audion tubes, one pole of which may be groundedat 20. q The batteries 21, 22 and 23, are the usual secondary or B batteries for supplying current tothe plates of the audion tubes.

I have shown 'at 2 a resistance connected across the primary battery 19, the center point of which is tapped and connected to the grid returns of thetubes 2, 3, 4 and 5. Connected to the center point of saidresistance is a by -pass condenser 25, the otherterminal of which connects to ground 20. At 126, I illustrate the, usual antenna or collector device which is used to pick up the signals that are to be received. 7 I a 7 Having described in general the apparatus used in connection with my arrangement, I will now briefly describe the functioning of the same. I v p .L The collector 126, is connected through the primary winding of .the transformer T to ground and the signals which are operative on said collector antenna 126 pass through said'primary winding to ground.

These signals are reproduced in the second- ;ary winding 26 of the transformer T and are operative upon the grid 27 of the audion tube 2. The audion tube 2 operates to repeat these signals from the grid 27 thereof to the plate 28 thereof and through the primary windin 29 of the transformer T to one pole of the l3 battery 22, which battery is connected in series with the other B batteries 21 and 23. The signals are inductively reproduced in secondary winding 30 of the transformer T and are operative on the grid of the audion tube 3, and are repeated thereby through the primary winding 31 of the transformer T Again the impulses are inductively operative through the secondary winding 32 of the transformer T. upon the grid of audion tube 4:, which repeats the signals through the rimary winding 34 of the transformer T. f'lere again the signals are operative through the secondary winding of transformer T 3 upon the grid of the detector tube 5. The detector audion tube 5 relays the signal through the primary 36 of the audio frequency transformer AT, where they are inductively repeated in the seconda 37 thereof, and areoperative upon the grid of the audion tube 6. The audion tube 6 repeats the signals through the primary 38 of'the audio frequency transformer AT and the signals are then inductively repro duced, upon the rid of audion tube 7, through the secondary 39 of audio transformer AT. The audion tube 7 reproduces the signals upon the plate circuit of the audion tube 7 which includes the reproducing device 18.

Referring now to transformers T and T as before noted, the tertiary windings of these transformers are bridged by'a variable condenser 10. This arrangement permits the tuning of the tertiary W1I1(llIl"S 8 and 9, which tuning inductively tunes the secondaries 26 and 30 of the transformers T and T to permitithe passage of only the desired signals and to exclude the undesired signals.

same is true of the variable air condenser 13 which tunes the tertiary windings 11 and 12- of the transformers T and T, which in turn inductively tune the secondaries 32 and 85 of the transformers T and T to resonance with the desired incoming signal thereby excluding the undesired signals It is thought unnecessary to go into further detial'of operation as the above description is thought sufiicient to enable any one skilled in the art to practice the invention.

From the foregoing, the ease of control of the tuning, Wlll readily be appreciated as it is only necessary to operate the variable condensers l0 and 13, each of which tunes two stages of amplification to adjust the set to any desired signal. The condenser 10tunes the tertiary windings in multiple of the transformers T and T and the condenser 13 tunes the tertiary in multiple of the transformer T and T. Of course, the

rheostats R, R R and R are adjusted to supply the correct heating current to the filaments of the audion tubes. I have found it possible to control more than two windings in multiple by one condenser.

I have found with the two main control. variable condensers 10 and 13 that three stages of radio frequency amplification and a. detector stage may be readily controlled to receive signals with great selectivity, clearness and amplification.

While I have shown aspecific circuit arrangement, I do not desire to be limited to the exact arrangement shown but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

What I claim as new and desire to secure by United States Letters Patent is:

1. A system of the character described including a plurality of transformers having primary, secondary and tertiary windings, and a single device having only one rotatable and only one stationary element for tuning said tertiary windings thereby simultaneously inductively tuning said secondary windings to a predetermined desired frequenczy. 2. system of the character described including a plurality of transformers having connected to said input and output circuits 7 of said transformers, tertiary windings for said transformers, and a single device connected in multiple with said tertiary windings for simultaneously tuning said tertiary windings, the tuning of said tertiary windings inductively tuning said output windings to resonate the same to a desired predetermined frequency.

4. An amplifying system of the character described including a pair of transformers having input and output windings, audion tubes associated with and havingelements connected to the said windings of said transformers, tertiary windings for said transformers, and a tuning device with a single stationary element for simultaneously tuning said tertiary windings thereby inductively tuning said output windings to resonate the same to a desired frequency.

5. A system of the character described including a pair of transformers having primary and secondary windings, audion tubes having elements connected to the said windings of said transformers, and a tertiary winding on each of said transform- 1 Evils ers adapted to be tuned by a device having one movable and only one stationary element to inductively tune said secondary windings,the tuning of said tertiary winding constituting the sole means for tuning the secondary windings to resonate the same to desired frequency.

6. A system of the character described including a plurality of stages of tuned amplification including transformers having primary and secondary windings, audion tubes having elements connected to the said windings of said transformers, tertiary windings for said transformers, and a single tuning device for multiple tuning of a plurality of said tertiary windings of said transformers to tune said transformers.

7. A system of the character described including a plurality of stages of tuned radio frequency amplification, transformers for said stages of amplification, and means including a single device having one movable and only one stator portion connected across windings associated with said transformers for simultaneously inductively tuning said transformers, the said last means constituting the sole means for tuning said transformers to a desired predetermined frequency.

8. A system of the character described including a plurality of stages of amplification involving audion tubes and transformers, circuit connections extending from the windings of said transformers to the elements of said tubes, and a single tuningdevice having one movable and only one stator element for simultaneously resonating windings of said transformers for inductively tuning said plurality of stages of amplification, said tuning devices constituting the sole means for resonating said stages to a desired frequency.

9. A tuning system of the character cletuned amplificatiomaudion tubes having elements, transformers having windings, circuits connecting the elements of said tubes to the windings of said transformers, other windings for said transformers, means including tuning devices having one stator element andonlyonerotorelementbridged across a plurality of said other windings for tuning scribed including a plurality of stages of tuned amplification involving audion tubes and transformers, circuit connections extending from the windings of said transformers to the elements of, said tubes,a plurality of tuning devices each having one movable and oniy one stationary element for simultaneously inductively tuning a greater number of said stages of tuned amplification, said tuning devices constituting the sole means for tuning said stages of amplification.

10. A system of the character described including a plurality of stages of tuned amplification involving transformers, audion devices having elements connected to windings of said transformers, and a plurality of tuning condensers each provided with a single rotor, element and a single stator element for simultaneously multiply inductively tuning said stages of amplification, each condenser being operable separately to tune a plurality of said stages of amplification.

11. A tuning system of the character described including a plurality of stages of 

